utime: New module. * lib/utime.in.h: Add comment for snippets. (utime): New declaration. * lib/utime.c: New file. * m4/utime.m4: New file. * m4/utime_h.m4 (gl_UTIME_H): Test for utime declaration. (gl_UTIME_H_DEFAULTS): Initialize GNULIB_UTIME, HAVE_UTIME, REPLACE_UTIME. * modules/utime-h (Depends-on): Add snippets. (Makefile.am): Substitute GNULIB_UTIME, HAVE_UTIME, REPLACE_UTIME. Insert snippets. * modules/utime: New file. * doc/posix-functions/utime.texi: Mention the new module.